Heat-Exchanger Plate

ABSTRACT

The present invention relates to a plate ( 1 ) for a flat-tube heat exchanger produced from a drawn metal sheet, said drawing enabling a fluid inlet ( 3   a ) and a fluid outlet ( 3   b ) to be connected together, said plate having a length (L) and a width (h), said fluid inlet and outlet ( 3   a,    3   b ) being located along the length (L) of the plate, spaced apart from the edge of the plate by a distance corresponding to L/2, which is approximately 40 mm, wherein the drawing forms a first fluid flow passage ( 5   a ) located on a first side of said fluid inlet and outlet ( 3   a,    3   b ) and a second fluid flow passage ( 5   b ) located on a second side of said fluid inlet and outlet ( 3   a,    3   b ).

The invention relates to the field of heat exchangers and moreparticularly flat tube heat exchangers used in the automotive field.

It is known practice in the automotive field to use heat exchangerscomprising a stack of identical flat tubes through which a first fluidcirculates. Each flat tube is formed of two sheets of metal sheet whichare chased to form a dish with a predefined pattern and are arranged insuch a way that their concave faces face one another. The two plates arethen joined together in a fluidtight manner, thus forming a flat tubethrough which a fluid can circulate from a fluid inlet to a fluidoutlet, the inlet and outlet each being situated at one end of the flattube, and more generally each being situated on opposite sides of theplate.

The flat tubes are stacked on top of one another, the fluid inlets ofeach flat tube being joined together to form an inlet column. Likewise,the fluid outlets of each flat tube are joined together to form anoutlet column. Between each flat tube is left a space for the passage ofa second fluid. The exchange of heat between the two fluids thereforetakes place as the first fluid passes through the flat tubes and thesecond fluid passes between said flat tubes.

It is also known practice, in order to increase the length of the flattube and therefore the area for exchange of heat between the two fluids,to have the flat tube follow a winding circuit by keeping ribs on theplates at the time of chasing. In this type of exchanger, the inlet andoutlet columns may thus be positioned on opposite sides of the plates oralternatively on the same side of the plates, as shown in applicationEP2105694.

Such heat exchangers are commonly used as evaporators in a refrigerantcircuit for air conditioning the interior of a motor vehicle, thisrefrigerant constituting the first fluid and the second fluid beingatmospheric air, or as a heating radiator in a heat transfer fluidcircuit for heating the interior of a motor vehicle, this heat transferfluid constituting the first fluid and the second fluid beingatmospheric air.

However, when a long exchanger is being used to cool a flow ofcompressed air acting as second fluid, for example on the outlet side ofa turbocompressor, and positioned as close as possible to the enginecombustion cylinder air inlets, there is a problem because of thepressure head loss caused by the length of plate needed to best coverthe surface area defined by all of the cylinders. Indeed, theeffectiveness of the cooling of the second fluid, in this instance air,decreases with increasing distance away from the inlet column for thefirst fluid, for example water or a refrigerant.

One of the objects of the invention is therefore to at least partiallyovercome the disadvantages of the prior art and to propose a heatexchanger that limits the pressure head loss of the plates.

The present invention therefore relates to a plate for a flat tube of aheat exchanger, which plate is made from a chased metal sheet, saidchasing allowing a fluid inlet and a fluid outlet to connect, said platehaving a length L and a width l, said fluid inlet and outlet beingsituated along the length at a distance from the edge of the plate thatcorresponds to L/2, plus or minus 40 mm, and the chasing forming a firstfluid flow passage situated on a first side of said fluid inlet andoutlet, and a second fluid flow passage situated on a second side, theopposite side to the first, of said fluid inlet and outlet.

According to one aspect of the invention, the first and second fluidflow passages are symmetric with one another about an axis of symmetrythat passes through the fluid inlet and outlet parallel to the width ofsaid plate.

According to one aspect of the invention, the chasing comprises ribsthat give the first and second passages a sinuous path comprisingabout-turns between the fluid inlet and the fluid outlet.

According to one aspect of the invention, the ribs have rounded ends.

According to another aspect of the invention, the first and second fluidflow passages comprise perturbation projections.

According to one aspect of the invention, the length of said plate isgreater than or equal to 400 mm.

The invention also relates to a flat tube for a heat exchangercomprising at least one plate according to the preceding aspects.

According to another aspect of the invention, the flat tube for a heatexchanger comprises a first and a second plate according to thepreceding aspects.

The invention also relates to a heat exchanger comprising at least oneflat tube according to the preceding aspects.

According to another aspect of the invention, said heat exchanger is acharge air cooler.

Other features and advantages of the invention will become more clearlyapparent from reading the following description, given by way ofnonlimiting illustrative example, among which:

FIG. 1 is a schematic depiction of a plate for a flat tube of a heatexchanger,

FIG. 2 shows a schematic depiction of a heat exchanger with a fluidcooling circuit.

The plate 1 for a flat tube of a heat exchanger depicted in FIG. 1 has alength L and a width h. The plate 1, made from chased sheet metal, has afluid inlet 3 a and a fluid outlet 3 b which are situated on the lengthL at a distance from the edge of the plate 1 that corresponds to L/2,plus or minus 40 mm. For preference, the fluid inlet 3 a and fluidoutlet 3 b are situated in the center of the length L of the plate 1.The chasing of the plate 1 forms a cavity with ribs 7 defining a firstand a second fluid flow passage 5 a and 5 b between the fluid inlet 3 aand the fluid outlet 3 b.

The ribs 7 give the first and second passages 5 a, 5 b a sinuous pathcomprising about-turns between the fluid inlet 3 a and the fluid outlet3 b. This sinuous path makes it possible to increase the length of thefirst and second passages 5 a, 5 b and therefore increase the time forwhich the fluid is flowing in said first and second passages 5 a, 5 b,thereby increasing the time in which there can be transfer of heat fromone fluid to another.

To facilitate this flow of fluid in the first and second passages, theribs 7 may have rounded ends 11.

The first and second fluid flow passages 5 a, 5 b are symmetric withrespect to one another about an axis of symmetry that passes through thefluid inlet and outlet 3 a, 3 b and is parallel to the width h of saidplate 1. What this means to say is that they are identical to oneanother and have the same shape and the same length.

The flow passages 5 a, 5 b may also comprise perturbation projections 9to make the fluid flowing along the flow passages 5 a, 5 b morehomogeneous.

The flat tubes consist of the assembly of two plates 1 joined together,the flow passages 5 a and 5 b of each of the two plates facing oneanother. The plates 1 are assembled in a fluidtight fashion, to preventany leaks of the fluid passing through the flow passages 5 a, 5 b.

Another way of embodying a flat tube may be to assemble a plate 1 with aflat plate resting on the periphery of the plate 1 and the ribs 7,covering the flow passages 5 a, 5 b.

A flat tube heat exchanger comprises a stack of flat tubes joinedtogether at their fluid inlet and at their fluid outlet 3 a, 3 b, eachflat tube being spaced apart so as to allow another fluid to passbetween said flat tubes. The flat tubes are joined together at the fluidinlet and outlet 3 a, 3 b to form a fluid inlet column that groupstogether all the fluid inlets of all the flat tubes and a fluid outletcolumn that groups together all the fluid outlets of all the flat tubes.

Because of the use of plates 1 according to the invention for producingthe flat tubes, the fluid inlet and outlet columns are situated at thecenter of the heat exchanger.

Thus, for the same length L of plate 1, and therefore of flat tube andof heat exchanger, the distance between the fluid inlets and outlets 3 aand 3 b and the end of the plate remains as short as possible, therebylimiting pressure head losses.

This feature is of all the more importance in heat exchanger flat tubeplates 1 of a length L greater than or equal to 400 mm. This is becauseit is for such a length L that the pressure head losses are significantin plates of the prior art.

Thus, in the case of a heat exchanger positioned as close as possible tothe engine combustion cylinder air inlets with a view to using arefrigerant circulating through the flat tubes to cool the flow of airarriving for example from a turbocompressor and rushing into eachcylinder, the fact that the refrigerant inlet and outlet 3 a, 3 b arecentered on the length L of the plates 1 means that said flow of air iscooled effectively even in the case of the combustion cylinders furthestaway from the refrigerant inlet and outlets 3 a, 3 b, thus reducing therisks of auto-ignition.

In addition, such a configuration of the plates 1 notably makes itpossible to obtain a heat exchanger 20 of the charge air cooler type,that is capable of cooling the same flow of air twice, as shown by FIG.2.

Thus, to cool a flow of air arriving from the exhaust circuit 22, saidflow of air is cooled a first time in the first flow passages 5 a,before it is compressed and therefore heated up in a turbocompressor 24.The flow of air passes once again through the heat exchanger in thesecond flow passages 5 b before rushing into the combustion cylinders26.

This configuration means that it is possible to have just onerefrigerant inlet column 30 a and just one refrigerant outlet column 30b, thus making it possible to overcome the constraints and costsassociated with the use of two heat exchangers which therefore requiretwo refrigerant inlet columns and two refrigerant outlet columns.

1. A plate (1) for a flat tube of a heat exchanger, which plate (1) ismade from a chased metal sheet which allows a fluid inlet (3 a) and afluid outlet (3 b) to connect, the plate (1) having a length (L) and awidth (h), wherein the fluid inlet and outlet (3 a, 3 b) are situatedalong the length (L) at a distance from the edge of the plate (1) thatcorresponds to L/2, plus or minus 40 mm, and wherein the chased metalsheet forms a first fluid flow passage (5 a) situated on a first side ofthe fluid inlet and outlet (3 a, 3 b), and a second fluid flow passage(5 b) situated on a second side, the opposite side to the first, of thefluid inlet and outlet (3 a, 3 b).
 2. The plate (1) as claimed in claim1, wherein the first and second fluid flow passages (5 a, 5 b) aresymmetric with one another about an axis of symmetry that passes throughthe fluid inlet and outlet (3 a, 3 b) parallel to the width (h) of theplate (1).
 3. The plate (1) as claimed in claim 1, wherein the chasedmetal sheet comprises ribs (7) that give the first and second fluid flowpassages (5 a, 5 b) a sinuous path comprising about-turns between thefluid inlet (3 a) and the fluid outlet (3 b).
 4. The plate (1) asclaimed in claim 3, wherein the ribs (7) have rounded ends (11).
 5. Theplate (1) as claimed in claim 1, wherein the first and second fluid flowpassages (5 a, 5 b) comprise perturbation projections (9).
 6. The plate(1) as claimed in claim 1, wherein the length (L) of the plate (1) isgreater than or equal to 400 mm.
 7. A flat tube for a heat exchangercomprising at least one plate (1) as claimed in claim
 1. 8. The flattube for a heat exchanger as claimed in claim 7, comprising a first anda second plate (1).
 9. A heat exchanger comprising at least one flattube as claimed in claim
 7. 10. The heat exchanger as claimed in claim7, which is a charge air cooler.
 11. The plate (1) as claimed in claim2, wherein the chased metal sheet comprises ribs (7) that give the firstand second fluid flow passages (5 a, 5 b) a sinuous path comprisingabout-turns between the fluid inlet (3 a) and the fluid outlet (3 b).12. The plate (1) as claimed in claim 2, wherein the first and secondfluid flow passages (5 a, 5 b) comprise perturbation projections (9).13. The plate (1) as claimed in claim 3, wherein the first and secondfluid flow passages (5 a, 5 b) comprise perturbation projections (9).14. The plate (1) as claimed in claim 4, wherein the first and secondfluid flow passages (5 a, 5 b) comprise perturbation projections (9).